Electric furnace



W. S. BURCH AND W. A. SCHELL.

ELECTRIC FURNACE.

APPLlcAloN FILED. JuLY 31.1919.

1,386,155. Patented Aug. 2,1921; n

INVENTUHS WM* .SGM

THE/R TTORNEY Wallin s.

UNITED STATES PATENT oFFicE.

A WALTER S. BURCH AND WILLIAM A. SCHELL, F ROCHESTER, NEW YORK, ASSIGNORS T0 ROCHESTER RAILWAY @c LIGHT COMPANY, OF ROCHESTER, NEW YORK, A CORm PORATION OF NEW YORK.

ELECTRIC FURNACE.

Specification of Letters'latent.

Patented Aug. 2, 1921.

Application flied July 31, 1919. Serial No. 314,409.

T0 all whom t may concern.'

Be it known that we, lVALTER S. BURCH and WILLIAM A. SCHELL, citizens of the United States, residing at Rochester, in the county of Monroe and State of New York, have invented certain new and useful lmprovements in Electric Furnaces; and we do hereby declare the following to be a Jfull, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to electric furnaces,

for the performance of chemical reactions at high temperatures. The invention is particularly applicable to the manufacture ot calcium carbid, although it may be used for various other reactions involving similar conditions. i

One object of the invention is to produce a furnace which will operate on the continuous-discharge principle, while avoiding the diiliculties which have been encountered in previous attempts to secure this result. To this end the furnace of the present invention is provided with electrodes of such form and arrangement that it is impossible for any unconverted solid particles to reach the discharge-passage of the furnace without passing through the sphere of operationof the electrodes. By the same form and ar rangement of parts the necessity of using refractory non-conductive material in close I'niiimity to the region of maximum temperature is avoided.

In revious attempts to produce continuons-discharge furnaces it has been proposed to permit the raw material to descend through a tube or reaction-chamber in which arcs are produced between electrodes projecting laterally into the chamber, the'escape of the material being unrestricted. In such a construction, however` at least where used with refractory materials such, for example, as calcium-carbid, particles of uncombined material are sure to escape the action of the arcs and to be discharged with the combined material.

On the other hand, it has been proposed to use an arrangement in which one electrode forms the bottom of the .reactions feed steadily to the electrodesbut tends to' arch and come to rest.

TheI present inventors have discovered that by a suitable arrangement ot electrodes it is possi-ble to produce a furnace possessing the advantages, and avoiding the defects, of both of the arrangements just described. This is accomplished by using two or more primary electrodes, which melt the bulk 0f the material and insure its continuous descent in the reaction-chamber, together with two or more refining electrodes which are so arranged that no particles of uncombined material can pass them. By the use of these two sets of electrodes in combination a furnace is produced which will act continuously and discharge a refinedI product free 'from unconverted raw-material.

Other objects ot' the invention, and the features of construction by which they are attained, will be. apparent from the following description of the illustrated embodiment of the invention.

In the accompanying drawings Figure 1 is a vertical median section of a furnace embodying the invention. F ig. 2 is a vertical sect-ion on the line 2 2 in Fig. 1. Fig. 3 is a detail plan-view of the bottom members of thefurnace. Figs. 4 and 5 are a vertical section and a plan-view of the bottom-members in a modified form.` Figs. 6 and 7 are diagrams showing two methods of energizin r the electrodes of the furnace.

The invention is illustrated as embodied in a furnace having a body 10 ot suitable refractory non-conducting material, which forms the wall of ay reaction-chamber 11. The bottom of the reaction-chamber, in the embodiment shown in Figs. 1, 2 and 3, is formed by two blocks 12 of graphite or carbon, together with two electrode-members 13, which are in contact at their inner extremities. These extremities are recessed, so as to provide. when in their normal engagement, a circular orifice 1.4 through which molten material is discharged from the furnace.

The members 13 also constitute, together, one of the electrodes of the furnace; and since they are in contact with the conductive blocks 12 the latter also contribute to their action and may be considered as a part of the same electrode, although this is not essential to the operation of the furnace.

In place of the two blocks 1:2 a single block or slab 18 of graphite or carbon may be used, as shown in Figs. 4 and 5, this slab being provided with a central opening 19 and with a transverse channel at the bottom in which the members 13 are seated.

Co `iperating with the bottom electrode is an electrode. 15 in the form of a graphite or carbon cylinder, which depends into the reaction-chamber directly in line with the discharge-orifice 14. rFhis central electrode moves vertically in a. refractory guide-tube 1G at the top of the furnace, and the vertical position of the holder and the electrode are controlled by suitable means such as ahoisting-tackle 17.

The discharge-orifice has a downwardlytapering form, as shown in the drawings, and the lower end of the central electrode 15 is pointed at a similar angle, so that when the central electrode is lowered toward the bottom electrode it acts as a needle-valve, by which the discharge-orifice may be controlled or entirely closed.

The electrodes 13 and 15 are connected, respectively, with the terminals of a source of current, so as to produce a current-flow, in a substantially vertical direction, through material in the bottom of the reaction chamber. lVhen the central electrode is adjusted close to but out of contact with, the bottom electrode all material escaping through the orifice 11 must first pass between the surface of the bottom electrode and the adjacent surface of the central electrode. Particles of solid unconverted material are thus prevented from falling directly through the outlet with the liquefied material, and are compelled to pass first through a narrow space where they are subjected to a highly concentrated heating effect, whereby they are fully converted and liquefied. The space between the electrodes may be made, by means of the tackle 17, as narrow' as may be necessary according tothe nature and purity of the materials and the quality of the product required.

In accordance with the broader aspects of the invention the perforated bottom electrode need not necessarily have the composite construction shown and described, but this construction affords convenient provision for maintaining the correct form of the outlet orifice, for upon withdrawal of the members 13 their ends may be dressed as may be required, to compensate for wear.

iVhile the bottom electrode and the cent 1al electrode perform the final refining and liquefying operation on the material, the furnace is provided with two or more primary electrodes 20, which enter the reaction-chamber laterally, and which are movable for the purpose of adjustment. These electrodes are spaced farther apart than the refining electrodes, while they project sufficiently beyond the firebrick walls to relieve the walls from the destructive temperature of reaction. These electrodes Q0 constitute, in the illustrated furnace, the main working members and are supplied with the greater part of the energy consumed in the furnace.

The several electrodes of the furnace may be energized in various ways, and the current between the primary electrodes and that between the refiningr electrodes are preferably under independent control. As Shown in Fig. i, the two sets of electrodes may be energized from two phases of a single polyphase system, or, as shown in Fig.

5 one set of electrodesimay receive alternating current while the other is fed with direct current. The lnumber of primary electrodes used is also variable, although two have been found to give satisfactory results.

The usual mode of operation of the furnace is as follows:

The central electrode 15 is lowered into engagement with the bottom electrode, so as to close the outlet-orifice against the premature escape of material. A charge of raw material is then introduced, and the current is a plied to the primary electrodes, thus heating and partly converting the material. The central electrode may then be energized and slightly lifted, thus permitting the material to escape as fast as it is refined and liquefied. iVith the normal operationthus established the central electrode is adjusted to the height at which the greatest production occurs without the escape of unconverted particles. The reaction-chamber is kept full by the addition of raw material as fast as it is consumed. The finished material is discharged into a pit 21 beneath the furnace, and the furnace is provided with peek-holes 22- normally closed by stoppers Q3, through which the operation may be observed. The raw material is introduced through openings 24, which are normally closed by doors 25, and flues 26, at the top of the furnace, discharge the fumes and gases resulting from the reactions in the furnace.

When it is desired to interrupt the operation of the furnace the current between all the electrodes is continued until the raw material remaining in the furnace is consumed,

and the energization of the electrodes 13, 15v

other forms Within the nature of the invention and the scope of the following claims.

The invention yclaimed is:

1. An electricfurnace comprising:a refractory body provided with a reactionchamber; an electrode, at the bottom of the chamber, comprisingl a plurality of retractable members normally in engagement and provided with recesses in their contiguous extremities constituting a discharge-opening; End a second electrode coperating with the 2. An electric furnace comprising: a refractory body provided with a reactionchamber; members of carbonaceous material, at the b ttom of the chamber, including a perforat n plate and a plurality of removable electrode-members meeting at the perforation in said plate and having a discharge-opening formed between their 'contiguous extremities and an electrode coperating with said electrode-members.

3. An electric furnace comprising: a refractory body provided with a reactionchamber.; primary electrodes operable upon material in said chamber; refining electrodes located below the primary electrodes and acting upon the material after its descent from the sphere of action of the primary electrodes, and means for regulating the escape of the refined material.

4. An electric furnace com rising: arefractory body provided wit a reactionchamber; primary electrodes in said chamber; a source of current for the primary electrodes; refining electrodes located below the primar electrodes and acting upon the material after its descent from the sphere.

of action of the primary electrodes, one of the refininv electrodes being adjustable toward and rom the other; and an independent source of currenty for the refining elecfractory body .provided with a reactionchamber' primary electrodes operable withn in said chamber; and refining electrodes 1ocated below the primary electrodes and closer together than the latter.

6. An electric furnace comprising: a refractory body provided with a .reactionchamber; primary electrodes operable within said chamber; and refining electrodes, between which the molten material escapes from the chamber, located below, and nearer together than theprimary electrodes.

An electric furnace comprising: a refractory body provided with a reactionchamber having an outlet at the bottom; electrodes arranged to pass a current horizontally through the upper part of/a body of material in said chamber; and independently operating electrodes arranged to pass 'current verticall through the lower part of said material adjacent to the outlet from the` chamber.

8'. An electric furnacecomprising: a refractory body rovided withy a reactionchamber; a con uctive bottom-member, for said chamber, provided with a ldischargeopening; a central electrode suspended in the chamber above said' bottom-member; electrodes projecting laterallyv into said chamber; and means for causing a discharge of current betweenithe central electrode and the bottom-member and also a discharge of current horizontally through the laterallydisposed electrodes. n

9. An electric furnace comprising: a body, of refractor material, provided with a reaction-cham er and with a discharge-opening; primary electrodes arranged to conduct current through the body of material in the reaction-chambery above the discharge-opening; an electrode operable upon the material at the 'discharge-opening; an electrode, cooperatin with the last-mentioned electrode, and projecting into'the material above the discharge-opening; a source of current for energizing the primary electrodes; and an independently controllable source of current for energizing the other said electrodes.

10. An electricfurnace comprising: a refractory body provided with a reactionchamber; an electrode, at the bottom of the chamber, provided with a discharge-opening; electrodes entering the chamber laterally; and a valve-member depending within the chamber and coperating with the firstmentioned electrode to adjustably restrict the discharge-opening.

WALTER s. BURCH. WILLIAM A. soHELL. 

